In recent years, the data amount processed by the storage system has been increasing. For this reason, the number of environments in which, apart from an older storage control apparatus used from the beginning, a new storage control apparatus is purchased, and the older storage control apparatus and the new storage control apparatus are concurrently used is increasing.
For example, firstly, logical volumes managed by the older storage control apparatus are assigned to a host computer. If the logical volumes are used by the host computer and the free capacity falls equal to or below a specified value, a new storage control apparatus is added to the storage system. Logical volumes managed by the new storage control apparatus are assigned to the host computer. Therefore, there is a problem that this complicates the storage system management.
For solving this problem, in a conventional technology described in the Patent Literature 1, an invention in which the host computer and a first storage control apparatus are connected via a first communication path, and furthermore the first storage control apparatus and a second storage control apparatus are connected via a second communication path is described.
With the conventional technology, a data input/output request from the host computer is received by the first storage control apparatus as a representative, and the first storage control apparatus and the second storage control apparatus cooperate to process the data input/output request. The first storage control apparatus, if receiving a first data input/output request of which the first storage control apparatus is not in charge, creates a second data input/output request corresponding to the first data input/output request. The first storage control apparatus transmits the second data input/output request to the second storage control apparatus via a second communication means. The second storage control apparatus processes the second data input/output request, and returns the result of the same to the first storage control apparatus. The first storage control apparatus transmits the processing result received from the second storage control apparatus to the host computer.